Muffler for a rotor vehicle internal combustion engine

ABSTRACT

A muffler is formed of an axially extending housing, and an exhaust gas pipe extending axially through the housing and enclosed within the housing by a tubular member. The tubular member is spaced outwardly from the pipe and inwardly from the housing and a sound-absorbing material is filled into the space between the tubular member and the muffler housing. Intermediate its inlet and outlet ends within the housing, the pipe has a constriction which provides a narrow flow passage between its upstream and downstream sides. The pipe has openings communicating with the space between it and the tube member on opposite sides of the constriction near its inlet and outlet ends within the muffler housing. Additional openings extend through the tubular member communicating with the space containing the sound-absorbing material. The ends of the tubular member are connected to the pipe adjacent its inlet and outlet ends within the housing.

United States Patent 1 [111 3,901,350

Loffelhardt Aug. 26, 1975 [54] MUFFLER FOR A ROTOR VEHICLE 1,343,005 10/1963 France 181/55 INTERNAL COMBUSTION ENGINE [75] Inventor: Dietmar Loffelhardt, Fellbach,

Germany [73] Assignee: J. Eberspacher, Germany [22] Filed: Sept. 16, 1974 [21] Appl. No.: 506,199

Related US. Application Data [63] Continuation of Scr. No. 384,067, July 30, 1973,

abandoned.

[30] Foreign Application Priority Data June 30, 1972 Germany 2232106 [52] US. Cl. 181/50; 181/55; 181/57 [51] Int. Cl. F0ln l/10 [58] Field of Search 181/36 B, 41-42, 181/47 R, 48, 49,50, 55, 68, 69

[56] References Cited UNITED STATES PATENTS 927,246 7/1909 Jackson 181/55 2,924,293 2/1960 Sprague 181/69 X 3,191,715 6/1965 .lettinghoff... 181/47 R 3,471,265 10/1969 Ciapetta 181/51 X 3,498,406 3/1970 Heath 181/53 3,527,472 9/1970 Chute 181/55 X FOREIGN PATENTS OR APPLICATIONS Belgium 181/33 f v V t; t

Primary ExaminerStephen J. Tomsky Assistant Examiner-Vit W. Miska Attorney, Agent, or Firm-Toren, McGeady and Stanger 5 7 ABSTRACT A muffler is formed of an axially extending housing, and an exhaust gas pipe extending axially through the housing and enclosed within the housing by a tubular member. The tubular member is spaced outwardly from the pipe and inwardly from the housing and a sound-absorbing material is filled into the space between the tubular member and the muffler housing. Intermediate its inlet and outlet ends within the housing, the pipe has a constriction which provides a narrow flow passage between its upstream and downstream sides. The pipe has openings communicating with the space between it and the tube member on opposite sides of the constriction near its inlet and outlet ends within the muffler housing. Additional openings extend through the tubular member communicating with the space containing the sound-absorbing material. The ends of the tubular member are connected to the pipe adjacent its inlet and outlet ends within the housing 5 Claims, 1 Drawing Figure PATENTEB AUG 2 61975 log.

MUFFLER FOR A ROTOR VEHICLE INTERNAL COMBUSTION ENGINE This is a Continuation of application Ser. No. 384,067, filed July 30, 1973 now abandoned.

SUMMARY OF THE INVENTION The present invention is directed to a muffler system for internal combustion engines in motor vehicles which consist of at least three mufflers and, more particularly, it concerns a muffler arrangement consisting of an exhaust gas pipe, a tubular member laterally enclosing the pipe and a muffler housing or jacket laterally enclosing both the tubular member and'thepipe.

Providing a silencing efiect for internal combustion engines has become increasingly important not only because of the interest in reducing the noise level to the human hearing system, but also because silencing has an effect on the engine, for example, back-pressure built up within the muffler.

Therefore, it has become increasingly difficult to develop a suitable muffler for each given engine, since each engine type has a different acoustic behavior and different pressure characteristics in the exhaust gas. Measures which afford a particularly good silencing effect in one engine, may be completely ineffective in another engine. Further, installation conditions in each vehicle are different and, as a result, limits are placed on the type of muffler for this reason.

It has been found to be advisable to use several individual mufflers in a muffler system, preferably two or three. In such systems, the mufflers consist of an exhaust gas pipe enclosed within a housing so that a chamber is formed around the pipe which can be subdivided into several compartments filled with soundabsorbing material. In these known arrangements, the exhaust gas pipe is frequently divided into individual sections which are staggered with respect to one another and which have gas outlet openings, for example, perforations, to afford the outflow of the exhaust fgas into the surrounding chamber and into other pipe sections. It is also known to connect a single chamber as a suction resonator in order to suck-off the pipe'resonance and thus to damp low frequencies. Finally, an interference effect is achieved by properly staggering the individual pipe sections.

To provide the muffling effect, it is principally known to use suction resonators, interfrequency and reflection chambers to attenuate low frequencies; and to use absorption chambers and filters for attenuating higher frequencies. Restrictors and perforations serve finally to smooth and finely disperse the exhaust gas current and to reduce pipe resonance.

The primary object of the present invention is to provide a muffler system, preferably consisting of two mufflers, suitable for use as a main muffler in which particularly good silencing is obtained in a constructionally simple manner.

It was found that it is possible to achieve adequate muffling with a relatively simple main muffler in highpower engines.

In accordance with the present invention, the problem of affording effective muffling is accomplished by providing the exhaust gas conveying pipe within the muffler with a radial constriction spaced from both ends of the muffler and with perforations or openings in the upstream and downstream sections of the pipe, that is in the portions of the pipe adjacent its inlet to and outlet from the muffler. Further, the exhaust gas pipe is coaxially enclosed by a tubular member also provided with gas outlet openings and the tubular member is connected at its opposite ends to the exhaust gas pipe. Laterally enclosing the tubular member and the exhaust gas pipe which it encloses, is a muffler housing with two transversely extending and rigidly connected end members. It is expedient if the space between the muffler housing or jacket and the tubular member enclosing the exhaust gas pipe is filled with sound-absorbing material. This arrangement affords additional muffling or silencing, preferably of the high frequencies by absorption. To improve the resonance behavior of the arrangement and to increase its strength, it is advantageous if the space filled with the sound-absorbing material is divided by at least one transversely extending partition into individual chambers. In this arrangement formed in accordance with the present invention, the exhaust gas flows through the inlet of the pipe and leaves the pipe at least partly through the perforations adjacent its inlet end and passes into the surrounding chamber (reflection chamber) formed by the tubular member, and re-enters the pipe through the second perforations located adjacent the outlet end of the pipe after flowing around the pipe. While this portion of the arrangement affords considerable silencing, the effect is further improved, as far as the attenuation of high frequencies is concerned, by the connection through the openings in the tubular member to the surrounding absorption chamber. This muffler construction influences the flow of the exhaust gases and has the effect that sound is equalized and a subjectively more pleasant sound pattern is obtained, since it is more harmonic and does not have the short sequence of vigorous sounds.

In another characteristic of the present invention, the radial constriction of the exhaust gas pipe is designed so that there is a gap or opening left for the flow of the exhaust gas at the point of greatest constriction, whereby a portion of the exhaust gas can continue to flow through the pipe. With regard to its manufacture, a particularly advantageous embodiment of the muffler is obtained by rolling the exhaust gas pipe from planar material with the abutting longitudinal edges being welded at spaced locations only.

The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this disclosure. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawing and descriptive matter in which there is illustrated and described a preferred embodiment of the invention.

' BRIEF DESCRIPTION OF THE DRAWING The drawing is a simplified and schematic illustration of a muffler embodying the present invention.

DETAILED DESCRIPTION'OF THE INVENTION In the drawing, an exhaust gas conveying pipe 6 extends through a muffler housing or jacket 1 with its central axis disposed obliquely to the central axis of the muffler housing. This arrangement results in an extension of the length of the pipe within the housing while affording a short overall length of the muffler.

The exhaust gas flows from the discharge elbow of the engine into the pipe 6 and, if necessary, passes through a pre-muffler which serves mainly to adjust the power of the enginev At its upstream or inlet end, the pipe 6, for about the first third of its axial length through the muffler housing, has a perforated section 10 through which the exhaust gas can flow out of the pipe. Following the perforated inlet section of the pipe a radial constriction 8 acts as a restrictor for the flow of exhaust gas through the pipe. The constriction is formed so that a gap or narrow flow passage 9 remains whereby the gas can continue to flow through the pipe 6. In the downstream or last third of the pipe 6, another perforated section 10a is provided through which exhaust gas from the pipe can escape.

Extending coaxially with the pipe 6 and concentrically surrounding it, is a tubular member 4. At its opposite ends, the tubular member 4 is secured by conical connections to the pipe 6 at a point upstream from the perforated section 10 and downstream from the perforated section 10a and within the range of the muffler housing 1. The tubular member 4 may be formed of two axially extending half-shell sections joined to one another for facilitating manufacturing and stockkeeping, and it has gas outlet openings 5 which serve as passageways into the space or chamber formed between the outer surface of the tubular member 4 and the inner surface of the muffler housing 1. The chamber between the tubular member and the muffler housing is filled with a sound-absorbing material 7.

At its transverse ends, the muffler jacket is closed by end members 2, 2a with the exhaust gas pipe 6 extending through the end members. Intermediate its end members, a partition 3 extends transversely of the housing and serves both to reinforce it and to separate it into two sub-chambers each filled with the soundabsorbing material 7.

While a specific embodiment of the invention has been shown and described in detail to illustrate the application of the invention principles, it will be understood that the invention may be embodied otherwise without departing from such principles.

'What is claimed is:

l.Muffler for an internal combustion engine of a motor vehicle, comprising an axially elongated imperforate tubular muffler housing, said muffler housing including an end member at each of its ends extending transversely of its axial direction and each said end member forming a closure for one end of said muffler housing and having an opening therethrough, an exhaust gas pipe having its axis extending generally in the axial direction of said muffler housing and extending through and spaced inwardly from said muffler housing, said exhaust gas pipe having an open inlet end and an open outlet end, said open inlet end extending through and forming a closure for the opening in one of said end members of said muffler housing and said outlet end extending through and forming a closure for the opening in the other end of said end member of said muffler housing, said pipe having an axially extending inlet section extending from its inlet .end toward said outlet end and an axially extending outlet section extending from its outlet end toward said inlet end and an intermediate section extending from said outlet section toward and spaced from said inlet section, said inlet section of said pipe extending for approximately A; of the axial length of said pipe from one end of said housing and said outlet section extending for approximately /3 of the length of said pipe from the other end of said muffler housing, a constriction formed in said pipe between said inlet section and said intermediate section and said constriction forming a narrow flow passage communicating between said inlet section and intermediate section, said inlet section, outlet section and intermediate section having substantially the same diameter, a plurality of openings formed in said inlet section and in said outlet section for affording communication with the space laterally enclosing said exhaust gas pipe and the portions of said inlet section and said outlet section containing said openings extending for a major portion of the axial length of said inlet section and outlet section, said constriction and said intermediate section consisting of the full axial length of said exhaust gas pipe between said inlet section and outlet section being imperforate, a tubular member positioned within and spaced inwardly from said muffler housing and laterally enclosing said pipe from a location upstream from the openings in said inlet section to a location downstream from the openings in said outlet section, the opposite ends of said tubular member upstream from the openings in said inlet section and downstream from the openings in said outlet section being connected to said pipe within said muffler housing, said tubular member having a plurality of openings therethrough along its axial length from said inlet section to said outlet section of said exhaust gas pipe with the openings communicating between the space between said exhaust gas pipe and said tubular member and spaced between said tubular member and said muffler housing, a sound-absorbing material filled into the space between said muffler housing and said tubular housing, and at least one partition disposed trans versely of the axial direction of said muffler housing and extending between said muffler housing and said tubular member intermediate said end members in the range of said intermediate section of said exhaust gas pipe so that said partition divides the space between said muffler and said tubular member into at least two separate axially extending chambers each containing said sound-absorbing material.

2. Muffler, as set forth in claim 1, wherein the central axes of said pipe and said tubular member are disposed coaxially and the central axes of said pipe and tubular member are disposed obliquely to the central axis of said muffler housing.

3. Muffler, as set forth in claim 1, wherein said tubular member comprises a pair of axially extending halfshell members secured together.

4. Muffler, as set forth in claim 1, wherein the opposite ends of said tubular member have axially extending conically-shaped sections which are connected to said pipe.

5. Muffler, as set forth in claim 1, wherein said pipe is formed of planar material rolled into a tubular form with the longitudinal edges of the joint secured together at spaced locations by welding. 

1. Muffler for an internal combustion engine of a motor vehicle, comprising an axially elongated imperforate tubular muffler housing, said muffler housing including an end member at each of its ends extending transversely of its axial direction and each said end member forming a closure for one end of said muffler housing and having an opening therethrough, an exhaust gas pipe having its axis extending generally in the axial direction of said muffler housing and extending through and spaced inwardly from said muffler housing, said exhaust gas pipe having an open inlet end and an open outlet end, said open inlet end extending through and forming a closure for the opening in one of said end members of said muffler housing and said outlet end extending through and forming a closure for the opening in the other end of said end member of said muffler housing, said pipe having an axially extending inlet section extending from its inlet end toward said outlet end and an axially extending outlet section extending from its outlet end toward said inlet end and an intermediate section extending from said outlet section toward and spaced from said inlet section, said inlet section of said pipe extending for approximately 1/3 of the axial length of said pipe from one end of said housing and said outlet section extending for approximately 1/3 of the length of said pipe from the other end of said muffler housing, a constriction formed in said pipe between said inlet section and said intermediate section and saId constriction forming a narrow flow passage communicating between said inlet section and intermediate section, said inlet section, outlet section and intermediate section having substantially the same diameter, a plurality of openings formed in said inlet section and in said outlet section for affording communication with the space laterally enclosing said exhaust gas pipe and the portions of said inlet section and said outlet section containing said openings extending for a major portion of the axial length of said inlet section and outlet section, said constriction and said intermediate section consisting of the full axial length of said exhaust gas pipe between said inlet section and outlet section being imperforate, a tubular member positioned within and spaced inwardly from said muffler housing and laterally enclosing said pipe from a location upstream from the openings in said inlet section to a location downstream from the openings in said outlet section, the opposite ends of said tubular member upstream from the openings in said inlet section and downstream from the openings in said outlet section being connected to said pipe within said muffler housing, said tubular member having a plurality of openings therethrough along its axial length from said inlet section to said outlet section of said exhaust gas pipe with the openings communicating between the space between said exhaust gas pipe and said tubular member and spaced between said tubular member and said muffler housing, a sound-absorbing material filled into the space between said muffler housing and said tubular housing, and at least one partition disposed transversely of the axial direction of said muffler housing and extending between said muffler housing and said tubular member intermediate said end members in the range of said intermediate section of said exhaust gas pipe so that said partition divides the space between said muffler and said tubular member into at least two separate axially extending chambers each containing said sound-absorbing material.
 2. Muffler, as set forth in claim 1, wherein the central axes of said pipe and said tubular member are disposed coaxially and the central axes of said pipe and tubular member are disposed obliquely to the central axis of said muffler housing.
 3. Muffler, as set forth in claim 1, wherein said tubular member comprises a pair of axially extending half-shell members secured together.
 4. Muffler, as set forth in claim 1, wherein the opposite ends of said tubular member have axially extending conically-shaped sections which are connected to said pipe.
 5. Muffler, as set forth in claim 1, wherein said pipe is formed of planar material rolled into a tubular form with the longitudinal edges of the joint secured together at spaced locations by welding. 